<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            display: flex;
            flex-direction: column;
            justify-content: center;
        }

        input {
            width: 150px;
            height: 20px;
            font-size: 20px;
        }

        #btn {
            width: 100px;
            height: 40px;
            font-size: 20px;
        }
    </style>
</head>

<body>
    <div>
        账号：<input type="text">
        密码：<input type="text">
        <!-- disabled禁用 -->
        <button id="btn">登录</button>
    </div>
    <script>
        let btnEle = document.getElementById('btn');
        btnEle.addEventListener('click', function () {
            // this.disabled=true;     //禁用
            this.disabled = false;     //可用
        });
    </script>
</body>

</html>